The separation of gas and liquid phases from a mixed phase material is useful in a variety of applications. One such application is in connection with fuel cells used for the production of electricity. For example, in a direct methanol fuel cell (DMFC) exhaust products, comprising H2O(g), H2O(l) and perhaps trace amounts of methanol recovered from the fuel cell stack cathode can be recycled to provide a makeup supply of H2O(l). Also, excess amounts of liquid methanol, water and product CO2 removed from the anode of the fuel cell stack maybe separated to provide a recycled supply of methanol and water. However, because of the limitations of existing systems for separating gases from liquids in mixed phase systems, providing a truly portable direct methanol fuel cell has been problematic.
The separation of gases from liquids in mixed phase systems has traditionally relied on gravity. Accordingly, existing gas/liquid separators are generally incapable of being used in any orientation. Although “clunk tanks” are available for providing a supply of gas-free liquids at any orientation, such systems do not provide true mixed phase separation. Other methods for separating gases from liquids are incapable of providing a liquid reservoir in connection with an orientation-insensitive system.
With reference now to FIG. 1, a conventional passive gas/liquid separator 100 is illustrated. The separator 100 includes a gravity separation reservoir or recovery tank 104. A mixed gas/liquid phase inlet 108, in communication with the fixed interior volume of the reservoir 104, supplies the mixed phase material to the reservoir 104. Under the influence of gravity, the liquid phase 112 is accumulated in the sump 116 of the reservoir 104, while the gas phase 120 is allowed to escape through a top-mounted vent 124. A hydrophobic membrane 128 may be used to prevent the loss of liquid 112 from the reservoir 104 should the reservoir 104 become tipped or inverted. The liquid 112 may be withdrawn through an outlet 132 located in the bottom of the sump 116. The separator 100 is incapable of reliably separating the gas phase 120 from the liquid phase 112 of the material when the separator 100 is oriented such that the vent 124 is below the outlet 132, or when the separator 100 is in a zero or near zero gravity environment.
With reference now to FIG. 2, a second conventional gas/liquid separator 200 is illustrated. In the separator 200, a mixed gas/liquid phase material is introduced through an inlet 204 into a fixed volume 208 that comprises a planar microporous hydrophobic membrane 212 and a planar hydrophilic membrane 216. The gas phase of the mixed gas liquid phase material is removed from a gas phase accumulating volume 220 through an outlet 224. The liquid phase passes through the hydrophilic membrane 216 and is accumulated in a liquid accumulating manifold 228. The liquid phase is then passed from the manifold 228 to a reservoir 232 by an outlet 236. In order to prevent the accumulation of any remaining gas phase material in the reservoir 232, a gas vent 240 is provided. An outlet 244 is provided for removing the liquid from the reservoir 232. Accordingly, the reservoir 232 portion of the gas/liquid separator 200 is orientation-sensitive. Although a reservoir 232 could be implemented as an accumulator that allows for orientation variance, such an implementation would result in a device in which any gases residual in the reservoir 232 are trapped until they are drawn out with the liquid.
For the reasons set forth above, there is a need for a system capable of separating gases from liquids in a mixed phase material that is orientation-insensitive. Furthermore, there is a need for such a system that provides a reservoir for a liquid phase of such material that is integrated with the gas/liquid separator. Furthermore, there is a need for such a system that reliably provides true phase separation.